JPH0778142B2 - Method for producing polyvinyl chloride foam - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for producing a polyvinyl chloride foam. More specifically, the present invention relates to a method for efficiently producing a polyvinyl chloride-based foam having a high expansion ratio, which enables a wall covering material, a flooring material, and the like having excellent designability and high strength.

[0002]

2. Description of the Related Art Conventionally, polyvinyl chloride foams have been widely used as materials for building materials such as wall coverings and flooring materials because of their excellent durability and flame retardancy. With changes in lifestyle and construction details, building materials with higher designability, flame retardancy and durability are required. Therefore, foams with high plasticity and high strength with a small amount of plasticizer are required. It has started to be done. However, in order to produce such a foam, it is necessary to reduce the amount of plasticizer used and to use a resin having a high degree of polymerization, and in this case, the melt viscosity at the decomposition temperature of the foaming agent should be within an appropriate range. Therefore, if the foaming is performed under the same foaming conditions, the expansion ratio is not sufficient, or unevenness is generated on the surface of the foamed product, so that a good foamed product cannot be obtained.
By the way, regarding the melt viscosity of plasticized polyvinyl chloride, the Florry equation is used.

[0003]

[Equation 2]

(In the formula, η is melt viscosity, Wp is resin fraction in resin-plasticizer system, Zp is molecular weight of resin, A, B and E are constants, R and T are gas constant and absolute temperature, respectively. ) Is well suited [Kinki Chemical Industry Association, Vinyl Division, "Polyvinyl Chloride II-Some Chemistry and Industry-", page 167 (published by Asakura Shoten in 1966)].
In the Florry equation, if the plasticizer is reduced, W
Since p becomes large, if the values of Wp ^1/2 and Zp ^1/2 are made to be the same, the molecular weight of the resin must be lowered to deal with it. However, in this case, since the foam obtained from the resin having a low degree of polymerization (low molecular weight) has a remarkably low strength, it causes an unfavorable situation such as damage during the construction of the product or deterioration of durability during use. . In addition, in order to create a foam with a reduced plasticizer without reducing the degree of polymerization of the resin, a compounding system in which the decomposition temperature of the foaming agent is on the high temperature side is processed at a higher temperature. However, in this method, there is a problem that a large amount of energy is required to obtain the foam and that the foam is easily discolored due to the high processing temperature.

[0005]

Under these circumstances, the present invention provides a high expansion ratio polyvinyl chloride foam having a low plasticizer content, a smooth surface, and sufficient strength. The present invention has been made for the purpose of providing a method of manufacturing with low energy consumption and without causing discoloration.

[0006]

DISCLOSURE OF THE INVENTION As a result of intensive studies conducted by the present inventors in order to achieve the above-mentioned object, polyvinyl chloride having a specific amount of epoxy groups bonded thereto is found to be a foaming decomposition process of an organic foaming agent. Focusing on the increase in the degree of polymerization, by using the epoxy group-bonded polyvinyl chloride for paste processing with a low degree of polymerization that gives an appropriate melt viscosity even with a low plasticizer amount, low energy consumption, sufficient strength and high It has been found that a foam having a low expansion ratio and a low plasticizer amount having a smooth surface can be easily obtained, and the present invention has been completed based on this finding. That is, in the present invention, in producing a solvent-soluble polyvinyl chloride-based foam in which the average degree of polymerization (P ₁ ) of the resin constituting the foam is 1000 or more,
(A) The average particle size is 0.05 to 5 μm, and the average degree of polymerization (P
₂ ) is smaller than P ₁ and the formula in the resin is

[0007]

[Equation 3]

Polyvinyl chloride for paste processing having an epoxy group bonded in the range represented by: (B) a plasticizer,
The present invention provides a method for producing a polyvinyl chloride-based foam, which comprises heat-foaming a plastisol containing (C) an organic foaming agent as an essential component. Hereinafter, the present invention will be described in detail. The polyvinyl chloride used in the present invention is required to have a spherical particle property having an appropriate particle size and particle size distribution for plastisol processing, and the average particle size is usually 0.05 to 0.55. It is in the range of 5 μm. If the particle size is larger than this, heating and melting will be delayed,
The effect of the present invention is not sufficiently exerted, and if the particle size is smaller than this, the viscosity of plastisol becomes too high, resulting in poor processability. Also, this polyvinyl chloride has an average degree of polymerization (P ₂ )
Must be less than 1000. This is because it does not increase the melt viscosity, therefore a suitable average degree of polymerization is selected depending on the type and amount of the plasticizer used, but if a smaller amount of plasticizer or high-speed foaming is desired,
It is desirable to select one with a lower average degree of polymerization. Furthermore, this vinyl chloride has the formula

[0009]

[Equation 4]

It is necessary that epoxy groups in the range of are bound. 62.5 in the above formula [2]
× P ₂ / Molecular weight value per bonded epoxy group is 0.2
If it is less than 5, the degree of polymerization of the resin in the foaming process is insufficient and the effect of the present invention is not sufficiently exerted. If it is more than 5, the degree of polymerization is excessively increased, and insolubilization of crosslinking occurs.
In post-processing of the foam, for example, embossing, it becomes difficult to create a good design. Such polyvinyl chloride is known as a general method for producing polyvinyl chloride for plastisol processing, for example, by using a vinyl chloride monomer, a monomer having an epoxy group, and a monomer copolymerizable with these, which is used as necessary. It is produced by copolymerizing by a known polymerization method such as fine suspension polymerization method, emulsion polymerization method, seed emulsion polymerization method, etc., and then drying the produced resin using a known drying method such as spray drying. be able to.

Examples of the monomer having an epoxy group include vinyl ethers such as vinyl glycidyl ether and allyl ethers such as (meth) allyl glycidyl ether, vinyl cyclohexene monoxide, butadiene monoxide, isoprene monoxide, and 1,4-pentadiene monoxide. Preference is given to epoxide olefins such as oxides and 1,5-hexadiene monoxide. These epoxy group-containing monomers have a smaller polymerization rate than vinyl chloride and are more susceptible to chain transfer, so that a small amount of epoxy groups can be uniformly bonded in the chain to give a resin having a low degree of polymerization. Since the thermal stability of the polymer is increased, the foam is less discolored, which is preferable. In some cases, glycidyl esters of unsaturated acids such as glycidyl methacrylate, glycidyl acrylate, glycidyl-p-vinylbenzoate, methylglycidyl itaconate, glycidyl ethyl malate, glycidyl vinyl sulfonate, and glycidyl (meth) allyl sulfonate should also be used. You can

On the other hand, examples of the copolymerizable monomer used as necessary include unsaturated monocarboxylic acid esters such as methyl, ethyl, propyl, butyl, octyl, cyclohexyl and benzyl esters of (meth) acrylic acid. , Unsaturated dicarboxylic diesters such as dimethyl, diethyl, dipropyl, dibutyl, dioctyl, dicyclohexyl and dibenzyl esters of maleic acid and fumaric acid, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether,
Vinyl esters of organic acids such as vinyl acetate and vinyl propionate, olefins such as ethylene, propylene, butene-1 and pentene-1, aromatic monovinyl compounds such as styrene and α-methylstyrene, acrylonitrile and methacrylonitrile, etc. Vinyl cyanide compound,
Further, polymerizable unsaturated compounds having no reactive functional group such as vinylidene chloride, acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, cinnamic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, etc. Unsaturated monocarboxylic acids, unsaturated dicarboxylic acids and acid anhydrides thereof,
Carboxyl group-containing polymerizable unsaturated compound such as unsaturated dicarboxylic acid monoalkyl ester such as maleic acid monoalkyl ester, fumaric acid monoalkyl ester, itaconic acid monoalkyl ester, 2-aminoethyl (meth) acrylate, 2-aminopropyl (Meth) acrylate, 3-aminopropyl (meth) acrylate, 2-aminobutyl (meth) acrylate, 3-aminobutyl (meth) acrylate, 4-aminobutyl (meth) acrylate, (meth) acrylamide, N-2-
Amino group-containing polymerizable unsaturated compounds such as aminoethyl (meth) acrylamide, N-2-aminopropyl (meth) acrylamide, N-3-aminopropyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate,
Hydroxyl group-containing polymerizability such as 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, dipentaerythritol hexa (meth) acrylate An unsaturated compound etc. are mentioned.

In the plastisol of the present invention,
The plasticizer used as the component (B) is not particularly limited, and an arbitrary one can be selected and used from those usually used for polyvinyl chloride plastisols. Examples of the plasticizer include dimethyl phthalate,
Diethyl phthalate, dibutyl phthalate, di- (2-
Ethylhexyl) phthalate, di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate, diphenyl phthalate, diisodecyl phthalate,
Ditridecyl phthalate, diundecyl phthalate, di (heptyl, nonyl, undecyl) phthalate, benzyl phthalate, butylbenzyl phthalate, dinonyl phthalate, phthalic acid derivatives such as dicyclohexyl phthalate, dimethyl isophthalate, di- (2-ethylhexyl) isophthalate , Isophthalic acid derivatives such as diisooctyl isophthalate, di- (2-ethylhexyl) tetrahydrophthalate, di-n-octyl tetrahydrophthalate, tetrahydrophthalic acid derivatives such as diisodecyl tetrahydrophthalate, di-n-butyl adipate, di- ( 2-ethylhexyl) adipate,
Adipic acid derivatives such as diisodecyl adipate and diisononyl adipate, azelaic acid derivatives such as di- (2-ethylhexyl) azelate, diisooctyl azelate, di-n-hexyl azelate, di-n-butyl sebacate, di- (2- Sebacic acid derivatives such as ethylhexyl) sebacate, maleic acid derivatives such as di-n-butyl maleate, dimethyl maleate, diethyl maleate, di- (2-ethylhexyl) maleate, di-n-butyl fumarate, di- (2- Fumaric acid derivatives such as ethylhexyl) fumarate, tri- (2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, triisodecyl trimellitate, triisooctyl trimellitate, tri-n-hexyl trimellitate,
Trimellitic acid derivatives such as triisononyl trimellitate, tetra- (2-ethylhexyl) pyromellitate, pyromellitic acid derivatives such as tetra-n-octylpyromellitate, triethyl citrate, tri-n-butyl citrate, acetyl Citric acid derivatives such as triethyl citrate, acetyltri- (2-ethylhexyl) citrate, monomethyl itaconate, monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, di- (2-ethylhexyl) itaconate, etc. Oleic acid derivatives such as itaconic acid derivatives, butyl oleate, glyceryl monooleate, diethylene glycol monooleate, methyl acetyl ricinoleate, butyl acetyl ricinoleate, glyceryl mono ricinoleate, di- Ricinoleic acid derivatives such as ethylene glycol monoricinoleate, stearic acid derivatives such as n-butyl stearate, glycerin monostearate, diethylene glycol distearate, and others such as diethylene glycol monolaurate, diethylene glycol dipelargonate, and pentaerythritol fatty acid ester. Phosphorus such as fatty acid derivative, triethyl phosphate, tributyl phosphate, tri- (2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris (chloroethyl) phosphate Acid derivative, diethylene glycol dibenzoate, dipropylene glycol dibenzoate Glycol derivatives such as triethylene glycol dibenzoate, triethylene glycol di- (2-ethylbutyrate), triethylene glycol di- (2-ethylhexoate), dibutylmethylenebisthioglycolate, glycerol monoacetate, glycerol triacetate , Glycerin derivatives such as glycerol tributyrate, epoxidized soybean oil, epoxy butyl stearate,
Epoxy Derivatives such as di-2-ethylhexyl hexahydrophthalate, diisodecyl epoxy hexahydrophthalate, epoxy triglyceride, epoxidized octyl oleate, epoxidized decyl oleate, adipic acid polyester, sebacic acid polyester, phthalic acid Polyester plasticizer such as polyester, or partially hydrogenated terphenyl, adhesive plasticizer,
Further, a polymerizable plasticizer such as diallyl phthalate and acrylic monomers and oligomers can be used. These plasticizers may be used alone or in combination of two or more.

The blending amount of these plasticizers may be smaller than that in the case of the conventional polyvinyl chloride plastisols, and is usually 10 to 100 parts by weight of polyvinyl chloride as the component (A).
It is selected in the range of 80 parts by weight, preferably 15 to 49 parts by weight. On the other hand, the organic foaming agent used as the component (C) in the plastisol of the present invention is not particularly limited, and any organic foaming agent generally used for foaming polyvinyl chloride may be selected and used. You can Examples of the organic foaming agent include azodicarbonamide, azobisisobutyronitrile, benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, p, p'-oxybis (benzenesulfonylhydrazide), dinitrosopentanemethylenetetramine, N, N. '
-Dinitroso-N, N'-dimethyl terephthalamide, trihydrazinotriamine and the like. These organic foaming agents may be used alone or in combination of two or more, and the amount thereof is usually 0.5 to 15 parts by weight per 100 parts by weight of the polyvinyl chloride of the component (A). Selected in a range of parts. If this amount is less than 0.5 parts by weight, foaming is insufficient, and if it exceeds 15 parts by weight, the expansion ratio does not improve for that amount, which is rather economically disadvantageous.

In the present invention, a foaming accelerator or a foaming inhibitor may be blended as desired to appropriately adjust the decomposition temperature of the organic foaming agent. Examples of the foaming accelerator include zinc oxide, lead stearate, calcium stearate, zinc stearate, barium stearate, and urea. Examples of the foaming inhibitor include maleic acid, organic acids such as fumaric acid, and maleic anhydride. , Acid anhydrides such as phthalic anhydride, acid halides such as stearoyl chloride and phthaloyl chloride, phenols such as hydroquinone and naphthalene diol, nitrogen-containing compounds such as aliphatic amines, heterocyclic amines, amides and oximes, Sulfur-containing compounds such as thiols, mercaptans, sulfonic acids, sulfoxides and sulfides, ketones such as cyclohexanone and acetylacetone, and 6,6
-Dimethylfulvene, hexachlorocyclopentadiene, dibutyltin maleate and the like.

If desired, the plastisol of the present invention may contain other additives conventionally used in polyvinyl chloride plastisols, such as inorganic fillers, heat stabilizers, viscosity modifiers, diluents, colorants, and additives. A flame retardant or the like can be added. Examples of the inorganic filler include calcium carbonate and magnesium carbonate such as precipitated calcium carbonate, ground calcium carbonate and ultrafine calcium carbonate, or silicates such as silica, talc, diatomaceous earth, clay and mica, and aluminum hydroxide. , Alumina, etc. can be used. Examples of the heat stabilizer include magnesium stearate, aluminum stearate, calcium stearate, barium stearate, zinc stearate, calcium laurate, barium laurate,
Metal soaps such as zinc laurate, sodium salts of phenol and naphthol, metal salts such as zinc and barium, organotin compounds such as dibutyltin dilaurate and dibutyltin dimaleate, diethylphosphite, dibutylphosphite, dioctylphosphite, diphenylisodecylphosphite. Examples thereof include phosphite esters such as phyto, tricresyl phosphite, triphenyl phosphite, tris (nonylphenyl) phosphite, and triisooctyl phosphite.

Examples of viscosity modifiers and diluents include xylene, solvent naphtha, mineral spirits,
Examples thereof include solvents such as diisobutyl ketone and butyl acetate, and suitable surfactants. Examples of the flame retardant include antimony trioxide, red phosphorus, zinc borate, organic bromide, and chlorinated paraffin. Further, the plastisol may be blended with polyvinyl chloride for ordinary plastisol processing having no epoxy group. In the method of the present invention, operations such as preparation of plastisol and application of plastisol, heat gelation, foaming, pretreatment, and posttreatment are carried out according to the equipment and conditions used for the production of a foam using a usual polyvinyl chloride plastisol. Can be applied. In this way, the plasticizer content is low,
And a foam with a high expansion ratio having a smooth surface is obtained,
This has an average degree of polymerization (P ₁ ) of the resin constituting 10
It is at least 00, is soluble in a solvent, and has sufficient strength. The solvent solubility of the present invention can be determined by a conventional method performed on a vinyl chloride resin or the like. For example, the fragment of the foam layer may be immersed in a good solvent for vinyl chloride resin such as tetrahydrofuran or methyl ethyl ketone to determine whether or not the fragment-shaped insoluble matter exists.

[0018]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. Each property was determined as follows. (1) Expansion ratio Thickness of the sheet-like expandable polyvinyl chloride layer before expansion (t
₁ ) and the thickness (t ₂ ) of the foamed layer after foaming by heating,
HICKNESS GAUGE "PEACOCK" [O
ZAKI MFG. CO., LTD. Product name] and the expansion ratio was determined according to the following formula. Expansion ratio = t ₂ / t ₁

(2) Surface smoothness The degree of unevenness of the foamed sheet was visually observed and evaluated according to the following criteria. ◯: Smooth Δ: Continuous spherical projections of about 0.5 mm exist ×: Continuous spherical projections of about 1 mm exist

(3) Whiteness The whiteness of the foamed sheet is measured by a color meter [made by Suga Test Instruments Co., Ltd.,
Yellowness (Y.I.) is measured using the product name], and the yellowness (Y.
The smaller the numerical value of I.), the better the whiteness, and the judgment was made as follows. ◯: YI less than 10 Δ: YI less than 10 to 13 X: more than YI 13

(4) Sharp edge property The degree of squareness at the convex portion of the embossed pattern of the embossed pattern and the concave portion of the wall paper having the largest step is visually observed and evaluated according to the following criteria. ◯: The corners are firm and the contours of the convex portions are clear. Δ: The middle of ○ to × ×: There is no corners and the thickness changes gently from the concave portions to the convex portions.

(5) Embossed punk The presence or absence of wrinkles other than the embossed pattern generated on the wall paper was visually observed and evaluated according to the following criteria. ◯: No wrinkles occurred ×: Wrinkles occurred

(6) Durability A foam sheet is cut into a size of 20 mm × 250 mm and DYED
MATERIAL FRICTION DURABIL
In TY TESTER (manufactured by Daiei Scientific Instruments Co., Ltd.), using Cerbon paper as an abrasive, replace the abrasive every 1,200 times, and perform a wear test up to 12,000 times to scrape the surface of the foam sheet and peel off the surface layer. Measure the number of abrasions up to and judge by the following. ◯: No damage even after 12,000 times x: Damage occurs after less than 12,000 times

(7) Average degree of polymerization of resin of foam layer 50 mm × 50 mm wall paper is used in tetrahydrofuran 50
Insoluble matter such as calcium bicarbonate dissolved in ml is removed by centrifugation. The supernatant liquid is added with methanol in an amount 20 times that of tetrahydrofuran to precipitate a polymer, which is filtered through a cylindrical filter paper, and then the methanol-soluble component is removed with a Soxhlet extractor using methanol and dried. Next, the average degree of polymerization of the obtained polymer was measured according to JISK-672.
Measure according to 1.

(8) Amount of Epoxy Group Bonded in Resin (Molecular Weight per Epoxy Group) After reprecipitation and purification of the resin in a tetrahydrofuran-methanol system, 1 g of the purified resin was added to 100 ml of methyl ethyl ketone.
300 ml of 1N hydrochloric acid solution 2 ml dissolved in
1) Place in a wide-mouth glass container equipped with a glass stopper, mix with a magnetic stirrer for 1 hour, and titrate with an alcohol solution of 1/10 N KOH (titration amount aml). On the other hand, the titration amount (bml) of the blank was obtained by the same operation without adding the resin, and the epoxy content (% by weight) in the resin was calculated by the following formula. The molecular weight per epoxy group is 20,
In the case of exceeding 000, the resin was measured again as 4 g. Molecular weight per epoxy group = W / {(b−a) f × 10 ⁻⁴ } f: Factor of 1/10 NKOH solution W: Weight of sample (g)

Examples 1 to 3 and Comparative Examples 1 to 3 Using vinyl chloride resins of the types shown in Table 1 and blending as shown below, a universal mixer [manufactured by Shinagawa Kogyo, 5-DM-R]
Mold] to mix for 15 minutes to prepare plastisol. Then, this plastisol was applied to flame-retardant paper with a Matisse oven [Warner Makis (Switzerland)] for 200
After being applied to a thickness of μm and solidified by heating at 150 ° C. for 45 seconds, it was heated and foamed at 210 ° C. for 60 seconds, and the expansion ratio, surface smoothness, and whiteness were measured at room temperature. Then, this is reheated with a far infrared heater for 8 seconds in an embossing unit of a Matisse oven to be embossed, and 250 mm x 400
A polyvinyl chloride foam wall paper of mm was obtained. With respect to this wall paper, the sharp edge property, embossed punk and durability were evaluated, and the average degree of polymerization of the resin in the foam layer was determined. The results are shown in Table 1.

Blending Vinyl chloride resin 100 parts by weight Dioctyl phthalate 40 parts by weight Heavy calcium carbonate (average particle size 2.3 μm) 30 parts by weight Azodicarbonamide 5 parts by weight Titanium oxide (rutile type) 12 parts by weight Na-Zn system Liquid stabilizer 3 parts by weight Antimony trioxide 3 parts by weight Mineral spirits 12 parts by weight

The symbols of the resins in the table mean the following. Resin A: Vinyl chloride having an average particle size of 1.3 μm, an average degree of polymerization of 730, and a molecular weight of 29,000 per epoxy group
Allyl glycidyl ether copolymer (62.5 × 730
/29,000=1.57) Resin B: vinyl chloride-glycidyl methacrylate copolymer having an average particle size of 1.7 μm, an average degree of polymerization of 750, and a molecular weight of 4,670 per epoxy group (62.5 × 750 /
4,670 = 10.0) Resin C: polyvinyl chloride having an average particle size of 1.2 μm and an average degree of polymerization of 720 Resin D: polyvinyl chloride having an average particle size of 1.2 μm and an average degree of polymerization of 1200 Resin E: average particle size 42 μm, vinyl chloride-vinyl acetate (4 wt%) copolymer of average resin 1000

[0029]

[Table 1]

Note 1) Since the foam was cross-linked, the amount of dissolved components was small and the amount of reprecipitated resin was small. As can be seen from Table 1, according to the method of the present invention, a foam having a high surface expansion and a high expansion ratio can be obtained, and a foamed product having good design and high strength can be easily obtained.

[0031]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a foam having a high expansion ratio and having a smooth surface even at a low plasticizer compounding range at a milder foaming temperature and a higher speed as compared with the prior art. As a result, a foamed product having a good design can be obtained. In addition, since the foam produced by the present invention is formed of a resin having a high degree of polymerization, it has high strength and little damage during transportation and use of the foamed product.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Nakano 1-2-1, Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan Zeon Co., Ltd. Research and Development Center (56) Reference JP-A-5-117436 (JP, A) )

Claims (2)

[Claims] 1. When producing a solvent-soluble polyvinyl chloride-based foam in which the average degree of polymerization (P ₁ ) of the resin constituting the foam is 1000 or more, (A) the average particle size is 0.05 to 5 μm. The average degree of polymerization (P ₂ ) is smaller than P ₁ and the formula (1) Plastisol containing as an essential component a polyvinyl chloride for paste processing having an epoxy group bonded in the range represented by the formula (B), a plasticizer (C) and an organic foaming agent (C). A method for producing a polyvinyl chloride foam. 2. The method for producing a polyvinyl chloride-based foam according to claim 1, wherein (A) is a copolymer of vinyl chloride and an epoxy group-containing vinyl ether, allyl ether or epoxide olefin.